To the Youth Hostel, take the motorway toward Lausanne and later toward Lausanne Sud. Continue up to the end of the motorway. It ends in a large roundabout called Rond-Point de la Maladière. Take the exit of the roundabout that is just before the one going back on the motorway, i.e. make almost a complete turn. From here, you are on the cantonal road towards Geneva, that is called Route de Chavannes. Turn left after 300 meters, on Chemin du Bois-de-Vaux. Follow the Youth Hostel signs.